1. Field of the Invention
The present invention relates to liquid fuel burning heaters, and more especially to compact, self-contained heater units suitable for use in vehicles, units that comprise a liquid fuel fed burner and a heat exchanger arranged in axial alignment inside a housing.
2. Description of the Prior Art
Various attempts have been made in the past to provide the heat exchanger part of heaters of the above-mentioned type in the form of a casting, considerable production economies being realizable, especially when the inner jacket which carries a number of radial fins is cast. It has also already been suggested to combine the burner housing with the finned inner jacket of the heat exchanger as a unitary casting, the jacket forming an axial extension of the burner housing. This simple structure has proved to be especially advantageous in the case of large production quantities, even though the initial assembly and any disassembly for servicing involve comparatively complicated procedures. Another shortcoming of this type of apparatus has to do with the susceptibility of the heat exchanger to premature destruction under heavy heat load, inspite of the general use of steel liners inside the inner jackets. Lastly, it has heretofore still been impossible to apply this type of structure to very compact heater units, where it is important to operate under comparatively high heating capacities, with correspondingly high specific heat loads on the heat exchanger walls.